The gable ends of our build will be constructed using local stone to meet a planning condition. The architect has suggested the use of Surecav units rather than blockwork. Has anyone got any experience of using Surecav, pros and cons etc?

http://www.surecav.com/en-GB/video_2.aspx

I'm sure he said local stone, SureCav, insulation, then block work, service void and plasterboard.

Does that sound right?

Can't see the point of the special stuff in the cavity, build it nicely with lime mortar = no probs

I looked into this product for our build and would have used it if we'd gone timber frame to benefit from the 100mm it would save compared to a cavity + block skin to support the stonework.

Twice the cost of the block wall though (based on NI rates) so depends how much the extra space or speed of construction is worth to you.

It can replace the outer leaf in a masonry build, but will probably dictate that the inner leaf is thicker to compensate structurally. Although you will need to use rigid board insulation, at least you will be able to ensure the inner leaf is clean and have good access to tape joints/make good around wall ties before fitting the Surecav and stone.

Careful workmanship?

I'm not aware of any alternative products that perform the same purpose, but I would expect building a typical ~200mm thick stone skin with a clear cavity would be difficult and expensive without something to back it up to.

There are veneers available in Ireland now that are cut from real stone in roughly 30-50mm thick pieces and crucially, there are "L" shaped pieces to wrap around corners and avoid the stuck on tile like appearance that let more traditional veneers down. Can be combined with brick slips if brick quoins are in keeping with the area. Cost should end up fairly close to a natural stone wall if the stone had to be bought.

Might be worth seeing if the veneers are available in a suitable stone for your locality and comparing the cost of a cavity wall clad in this to the other approach. It all depends on the area of stonework you're looking to build...

Posted By: TriassicMy architect thinks natural stone requires support of some sort?!

This depends on his assumption of the thickness of the stone. 250mm done properly shouldn't need support. Thinner than that - well this depends on the stone and the stone mason.

An architect will always err on the side of caution because it's too expensive for him not to.

Building a stone wall can be much quicker if you are building to a flat vertical backing of some sort so some labour savings will help defray the cost of the backing. Much could depend on the skill set of the builder.

One property the stone does add to the build up is the ability to smooth out temperature swings when bright, hot days are followed by cool, cloudless nights.

The big challenge we found on our build (wide cavity) was minimising thermal bridging at the openings with 200mm stone facing as the windows are in the same plane as the outer block skin. This is partly because there are limited options for depth of granite cills and partly because the windows would look odd and be overly shaded if placed too far back.

My solution was to enlarge the opening size in the outer block skin by 100mm at the top and sides and inserting strips of PIR around the frame. This still left a slight pinch point in the insulation, but with a bit more thought I found a way to improve that by a factor of three.

Using Surecav, or an equivalent product, would place the front of the window in the cavity and it may be possible to insulate around this.

SureCav (& similar) are designed to provide a level background for the stonework to be built up against and at the same time, keep the cavity clear, so that no mortar snots bridge it, and also keep the insulation tight back to the inner leaf.
Does that make sense..?

So if I have natural stone I have though a cavity?

Edit.. So how come EWI does not have a cavity, is it because the rendering is waterproof?